Extension, fiber

In the early 1990s, there were more than 9 x 10 km of fiber-optical telecommunication links in practical use in the United States. In addition, many other countries, notably Canada, Japan, and western Europe, have installed extensive fiber-optic communication systems. There are several transoceanic fiber-based telephone cables. Fibers are in use for intracity telephone links, where bulky copper [7440-50-8] wine is replaced by thin optical fibers. This allows crowded conduits in large cities to carry more messages than if copper wine were used. Fiber optics are used for intercity long-haul telephone links, for interoffice tmnk lines, and have replaced many microwave communication links. 

The flexural and tensile properties of polyester composites at various fiber volume fractions are listed in Table I. Strength values increase up to a fiber volume fraction of about 40% but then decrease with increased fiber volume fraction. This is caused by the poor wetting and extensive fiber damage which occurs at higher volume fractions because of compaction and close packing of the fibers. The ultimate flexural strain shows a similar trend. The modulus values increase almost linearly with fiber volume fraction. 

Carbon fiber/Si3N4 composites were fabricated using slip infiltration of fiber bundles, subsequently stacked in a plaster mold, dried, glass encapsulated and HfPed to form unidirectional composite test bars. Neither chemical reactions between fiber and matrix, nor thermal mismatch cracks in the matrix were observed. The bend fracture behavior of the composites was non-brittle with extensive fiber pullout. 

Abstract The fanlike extension fibers of the anterior cruciate ligament (ACL) adhere to the bone surface regardless of the knee flexion angle, the fiber location and orientation do not change, in relation to the femoral surface. However, the ACL midsubstance fiber orientation related to the femur does change during knee motion. 

Static and Dynamic Observation of the Fanlike Extension Fibers... 

At full extension, both fiber types were aligned parallel to the intercondylar roof without deviation (Figs. 1.1a and 1.2a). The midsubstance fiber attachment area was observed to be slightly protuberant, compared with that of the fanUke extension fibers (Fig. 1.2a). The seemingly thin and coarse fanlike extension fibers came into... 

Fig. 1.1 Midsubstance and fanlike extension fibers during flexion-extension of the knee (From [20] with permission)...

With knee flexion of 15 and 30°, the midsubstance fibers were slightly curved anterior to the articular cartilage of the lateral condyle (Fig. 1.1b, c). The border between the midsubstance fibers and the fanlike extension fibers was then distinct (Fig. 1.2c). The location and orientation of the fanlike extension fibers, in relation to the femoral condyle surface, did not change, due to adherence to the bone surface (Fig. 1.2d). 

The attachment of the midsubstance fibers was significantly smaller than that of the fanlike extension fibers. The fold ratio (midsubstance attachment/whole ACL attachment) was 63.7 % (47.3—80.2 %). The attachment area of the fanlike extension fibers was approximately twofold the midsubstance fibers. 

With knee flexion at 120°, a fold in the midsubstance fibers was noted several millimeters from the bone surface (Fig. 1.3a-d). The thin fanUke extension fibers adhered to the bone surface in the same manner as that observed in the full extension position. The angle between the fanlike extensimi fibers and the midsubstance fibers was >90°. The area between the collagen fibers and the bone in the midsubstance fiber insertion comprised a cartilaginous zone, despite that... 

The most important finding of the present study [20] was that because the fanlike extension fibers adhered to the bone surface, the fiber location and orientation in relation to the femoral surface did not change, regardless of the knee flexion angle, while orientation of the midsubstance fibers in relation to the femur did change... 

This study demonstrated the two types of attachment margins of ACL (1) the relatively narrow oval attachment margin of the midsubstance fibers of ACL and (2) the broader attachment margin of the fanlike extension fibers. The previous studies were thus confirmed regarding the correct information on a part of the ACL attachment. Those previous studies might have observed one or both of these two attachment margins. 

Recently, though some studies recommend creation of a femoral tunnel to reconstruct the AM bundle of the ACL [13, 37], such a method may not achieve reconstruction of the normal ACL in terms of function and morphology for the following reasons. The fanlike extension fibers contributed only 15% of the... 

Abstract Identification of the anatomical anterior cruciate ligament (ACL) footprint is essential in femoral tuimel preparation. The lateral intercondylar ridge (LIR), which is termed the anterior border of the femoral ACL footprint, can be used as a landmark during surgery. The entire ACL footprint consists of the direct insertion of the ACL located behind the LIR and the attachment of fanlike extension fibers extended to the posterior cartilage margin. The lateral bifurcate ridge can be observed between the attached anteromedial (AM) and posterolateral (PL) bundles in 80 % of cases. 

Fig. 25.1 A deep fold is formed at the border between the mid-substance and the fanlike extension fibers during knee flexion. Therefore, it is meaningless to reconstruct the fanlike extension fibers in ACL reconstruction. However, the mid-substance fibers of the AM and PL bundles can be reconstructed by creating two tunnels at the center of the femoral direct attachment of the AM or PL mid-substance fibers, respectively...

Another test method for resin-fiber bond strength employs a single fiber embedded within a long resin bar (154). As the bar is stretched, the less-extensible fiber breaks into smaller and smaller fragments with a final mean length of / Originally, T was interpreted in terms of a characteristic failure stress Ug of the resin-fiber bond in shear (155) ... 

---